lkml.org 
[lkml]   [2003]   [Jan]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: PCI code: why need outb (0x01, 0xCFB); ?
Nakajima, Jun wrote:
>
> Normally all accesses should be long (0xcf8/0xcfc) but x86 is byte addresseable and some chipsets do support byte accesses.
> We do not encourage use of byte accesses as it will not be supported in future platforms.
>

The PCI standard is quite explicit: byte accesses are permitted to the
data window (0xCFC) and not permitted to the address window (0xCF8).
Accepting byte accesses to the address window, or not supporting byte
accesses to the data window, *will* result in breakage (I can attest to
this fact quite well.)

-hpa


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:32    [W:0.029 / U:1.328 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site